Set the center of the scaling with the mouse or enter a coordinate in the command line.

The scale dialog is displayed where you can enter the scale factor. If you want to scale with two different factors in X and Y direction, uncheck the button for proportional scaling: You can then enter two different scaling factors for X and Y. If you want to scale the selection by mouse, check the mouse cursor button:

Click "OK".

If you have previously chosen to scale the selection by mouse, you now have to specify a reference point and a target point for the scaling operation.